Influence of environmental conditions and voltage application on the electromechanical performance of Nafion-Pt IPMC actuators

Abstract

Ionic Polymer-Metal Composites (IPMCs) are a class of Ionic-type Electroactive Polymers (I-EAPs) which can be configured as capacitor actuators with very low voltage requirements (≤ 5 V AC or DC). Their compact, portable, and lightweight properties, coupled with a biomimetic bending actuation response, makes them ideal for human-machine integrated technologies such as medical implants, active skins, and artificial muscles. Unfortunately, IPMC actuator’s hydration-related sensitivity inhibits practical application in industry and makes experimental research difficult. Therefore, this research sought to quantify the hydration-related parameters of IPMC actuators by applying a wide range of experimental tests to characterize the material’s hydration-dependent features. This included saturation, dielectric, and bending actuation measurements. The IPMC’s degree of saturation properties were classified to establish sample rehydration, preparation, and preservation techniques. IPMC electrical-solvent properties were measured to estimate IPMC actuation performance based on capacitance and dissipation measurements. Maximized actuation was identified for samples tested in 95 % RH (i.e., percentage relative humidity). This condition produced a optimized displacement range and retained quality. Through statistical analysis, the work showed large electroactive performance variability (up to 50% deviation), which is a primary obstacle inhibiting this technology from practical application. Finally, an array of electrical field bias applications (i.e., cycled, constant, and post voltage removal monitoring) at intensities ranging from 0.75 to 1.2 direct current voltage (DCV) were used to quantify actuation rate, maximum displacement, as well as voltage application and removal back-relaxation behavior.

Nafion-Pt IPMC electroactive behavior changes in response to environmental nonequilibrium conditions

“…The 85% RH condition was chosen as the last point before a significant drop off in dielectric and dissipation quality (see setting 0.85 in figure 1(a), ε ′ = 1.32 × 10 6 ± 2% and also note t = 8 h in figure 1(b) where tan δ = 8.6 ± 11%). This also correlated with regions of interest in reported hydration studies [9,16,45]. Lastly, 70% RH was chosen as it was located after the dielectric properties diminished significantly (see environment setting 0.7 in figure 1(a) yielding ε ′ = 1.42 × 10 5 ± 44%) and t = 10 h in figure 1(b) where tan δ = 24.6 ± 15%).…”

“…DI water conditions produced dielectric values of ε ′ = 1.21 × 10 6 ± 25%, with dissipation of tan δ = 6.5 ± 33%. The 96% RH setting was chosen as the 'ideal operating environment' in a prior study and therefore was used for comparison and validation in this work [16,45]. The ideal (or maximized displacement) operating environment is classified in this work as being any ambient conditions which produce optimized IPMC performance.…”

Carbon‐Based Nanomaterials Electrodes of Ionic Soft Actuators: From Initial 1D Structure to 3D Composite Structure for Flexible Intelligent Devices

“…Additionally, carbon-based nanomaterials and combined electrodes only need general simple manufacturing processes such as casting drying and hot press (Figure 2a) to obtain ion actuators with excellent performance. [102][103][104][105][106][107][108][109] The driving mechanism of the ISA with CBNs is based on intercalation and delamination of ions. As shown in Figure 2b, the cation and anion ions in the interlayer electrolyte will diffuse to the electrode layer under the action of the electric field.…”

“…Additionally, carbon‐based nanomaterials and combined electrodes only need general simple manufacturing processes such as casting drying and hot press ( Figure a) to obtain ion actuators with excellent performance. [ 102–109 ]…”

Growth simulation based on diffusion-limited aggregation method for dendritic interfacial electrodes inside IPMC

“…DIEs inside IPMC include the surface layer, particle layer and dendritic interfacial layer, as shown in figure 1(b). In order to clarify the mechanism and influence factors of electrode formation inside IPMC, some physical models have been developed [14][15][16]. Kim et al proposed a particle aggregation model for studying the parameters of the electrode [17].…”